# Task
 Given a string `str`, reverse it omitting all non-alphabetic characters.

# Example

 For `str = "krishan"`, the output should be `"nahsirk"`.
 
 For `str = "ultr53o?n"`, the output should be `"nortlu"`.
 
# Input/Output


 - `[input]` string `str`

  A string consists of lowercase latin letters, digits and symbols.

 
 - `[output]` a string

Difficulty: EASY
Starter code: def reverse_letter(string):
	

Solutions:
def reverse_letter(s):
	return ''.join([i for i in s if i.isalpha()])[::-1]


reverse_letter = lambda s: ''.join([i for i in s if i.isalpha()])[::-1]


def reverse_letter(string):
	return ''.join(filter(str.isalpha, reversed(string)))


import re

def reverse_letter(string):
	return re.sub('[^a-zA-Z]', '', string)[::-1]


def reverse_letter(string):
	return ''.join((c for c in string[::-1] if c.isalpha()))


def reverse_letter(s):
	return ''.join(filter(str.isalpha, s))[::-1]


reverse_letter = lambda s: ''.join(reversed([x for x in s if x.isalpha()]))


def reverse_letter(string):
	result = ''
	for char in string:
		if char.islower():
			result = char + result
	return result


def reverse_letter(string):
	return ''.join((i for i in string[::-1] if i.isalpha()))


def reverse_letter(string):
	str = ''
	for n in string:
		if n.isalpha():
			str = n + str
	return str


import re

def reverse_letter(string):
	return ''.join(re.findall('[A-Za-z]', string)[::-1])


def reverse_letter(string):
	new_string = ''
	alphabet = 'abcdefghijklmnopqrstuvwxyz'
	for i in string:
		if i in alphabet:
			new_string += i
	return new_string[::-1]


import string

def reverse_letter(string):
	return ''.join(filter(str.isalpha, string))[::-1]


def reverse_letter(string):
	a = []
	for i in string:
		if i.isalpha():
			a.append(i)
	return ''.join(list(reversed(a)))


def reverse_letter(string):
	rev = string[::-1]
	return ''.join([x for x in rev if (x if x.isalpha() else None)])


reverse_letter = lambda s: ''.join(filter(str.isalpha, s[::-1]))


def reverse_letter(string):
	return ''.join((char for char in string[::-1] if char.isalpha()))


import string

def reverse_letter(s):
	return ''.join(reversed([a for a in s if a in string.ascii_letters]))


def reverse_letter(string):
	return ''.join((s for s in reversed(string) if s.isalpha()))


def reverse_letter(string):
	revstr = string[::-1]
	return ''.join([x for x in list(revstr) if x.isalpha()])


reverse_letter = lambda string: ''.join([i for i in string if i.isalpha()])[::-1]


reverse_letter = lambda s: ''.join((c for c in reversed(s) if c.isalpha()))


import array

def reverse_letter(string):
	a = array.array('u', string)
	a.reverse()
	return ''.join(filter(lambda x: x.isalpha(), a))


import re

def reverse_letter(string):
	return re.sub('[^a-z]', '', string[::-1])


def reverse_letter(string):
	string = str().join(list(filter(str.isalpha, string)))
	return string[::-1]


def reverse_letter(string):
	return ''.join((x for x in reversed(string) if x.isalpha()))


reverse_letter = lambda s: ''.join(filter(lambda x: x.isalpha(), s))[::-1]


def reverse_letter(string):
	return ''.join((x for x in string[::-1] if x.isalpha()))


reverse_letter = lambda s: ''.join((l for l in s if l.isalpha()))[::-1]


def reverse_letter(string):
	txt = ''
	for a in string:
		if a.isalpha():
			txt = txt + a
	return txt[::-1]


def reverse_letter(string):
	array = list(filter(str.isalpha, string))
	new_list = ''.join(array)
	return new_list[::-1]


def reverse_letter(string):
	string = string[::-1]
	string2 = ''
	for x in range(0, len(string)):
		if string[x].isalpha():
			string2 += string[x]
	return string2


import re

def reverse_letter(st):
	newst = st[::-1]
	itog = ''
	for i in newst:
		if i.isalpha():
			itog += i
	return itog


import string

def reverse_letter(str):
	chars = string.ascii_lowercase
	return ''.join((i for i in str[::-1] if i in chars))


def reverse_letter(string):
	alphabet = 'abcdefghijklmnopqrstuvwxyz'
	newString = ''
	for letter in string:
		if letter in alphabet:
			newString += letter
		else:
			continue
	return newString[::-1]


def reverse_letter(string):
	word = []
	for i in string:
		if i.isalpha() == True:
			word.append(i)
	word = reversed(word)
	word_rev = ''.join(word)
	return word_rev


def reverse_letter(string):
	chars_only = ''
	for item in string:
		if item.isalpha():
			chars_only += item
	return chars_only[::-1]


def reverse_letter(string):
	return ''.join([i if i.isalpha() else '' for i in reversed(string)])


def reverse_letter(string):
	a = []
	a[:] = string
	a.reverse()
	b = []
	c = ''
	let = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
	for s in a:
		if s in let:
			b.append(s)
	for ele in b:
		c += ele
	return c


def reverse_letter(string):
	new = [s for s in string if s.isalpha()]
	a = new
	a.reverse()
	return ''.join(list(a))


def reverse_letter(string):
	return ''.join(reversed([char for char in string if char.isalpha()]))


import string

def reverse_letter(string):
	phrase = []
	alpha = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
	for letter in string:
		if letter in alpha:
			phrase.append(letter)
	return ''.join(reversed(phrase))
reverse_letter('hello')


def reverse_letter(string):
	alphabet = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}
	a = list(string)
	new = []
	for k in range(0, len(a)):
		if a[k] in alphabet:
			new.append(a[k])
	b = list(range(0, len(new)))
	for i in range(0, len(new)):
		b[i] = new[len(new) - 1 - i]
	out = ''
	for j in range(0, len(new)):
		out += str(b[j])
	return out


def reverse_letter(string):
	result = ''
	for letter in string:
		if letter.isalpha():
			result += letter
		else:
			del letter
	result2 = result[::-1]
	return result2


def reverse_letter(string):
	return ''.join(list(reversed([n for n in string if n.isalpha()])))


def reverse_letter(string):
	reversed = ''
	for char in string:
		if char.isalpha():
			reversed += char
	return reversed[::-1]


def reverse_letter(string):
	n = len(string)
	str = ''
	for i in range(n):
		if string[i].isalpha() == True:
			str = str + string[i]
	return str[::-1]


def reverse_letter(string):
	newString = ''
	for word in string:
		if word.isalpha():
			newString = word + newString
	return newString


def reverse_letter(string):
	r = len(string)
	s = ''
	for i in range(r):
		if string[i].isalpha():
			s = s + string[i]
	return s[::-1]


import re

def reverse_letter(string):
	return re.sub('[0-9!@#$%^&*?/ \\/(/)/{/}/+/-/*/[/\\]/~/`/./,/>/</\'/"/?\\=\\\\:_|\\-;]', '', string)[::-1]


def reverse_letter(string):
	s = ''
	for c in string[::-1]:
		if c.isalpha():
			s += c
	return s


letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']

def reverse_letter(string):
	string = string[::-1]
	returner = []
	for item in string:
		if item in letters:
			returner.append(item)
	return ''.join(returner)


def reverse_letter(string):
	result = ''
	for i in range(1, len(string) + 1):
		if string[-i].isalpha():
			result += string[-i]
	return result


def reverse_letter(string):
	x = filter(str.isalpha, string)
	return ''.join((i for i in list(x)))[::-1]


import string

def reverse_letter(s):
	abc = list(string.ascii_lowercase)
	result = []
	for i in s[::-1]:
		if i in abc:
			result.append(i)
	return ''.join(result)


def reverse_letter(string):
	answer = []
	for a in string[::-1]:
		if a.isalpha() == True:
			answer.append(a)
	return ''.join(answer)


def reverse_letter(string):
	ls = list(string)
	reverse = ls.reverse()
	reversed_cleaned = ''
	for i in range(len(ls)):
		if ls[i].isalpha():
			reversed_cleaned += ls[i]
	return reversed_cleaned


def reverse_letter(string):
	reversed = ''
	length = len(string)
	for m in range(length):
		reversed = reversed + string[length - 1 - m]
	abc = 'abcdefghijklmnopqrstuvwxyz'
	reversed_cleaned = ''
	for n in range(length):
		if reversed[n] in abc:
			reversed_cleaned += reversed[n]
	return reversed_cleaned


def reverse_letter(string):
	res = ''
	for i in range(len(string) - 1, -1, -1):
		if string[i] in 'abcdefghijklmnopqrstuvwxyz':
			res += string[i]
	return res


def reverse_letter(a):
	ans = ''
	a = list(a)
	while len(a) > 0:
		b = a.pop()
		if b.isalpha():
			ans = ans + b
			print(ans)
	return ans


def reverse_letter(string):
	arr = list(filter(str.isalpha, string))
	arr.reverse()
	return ''.join(arr)


def reverse_letter(string):
	str = ''.join([x if x.isalpha() else '' for x in string])
	return str[::-1]


def reverse_letter(string):
	gnirts = ''
	for i in range(0, len(string)):
		if string[i].isalpha():
			gnirts = string[i] + gnirts
	return gnirts


def reverse_letter(string):
	alphabet = 'abcdefghijklmnopqrstuvwxyz'
	s = ''
	for letter in string:
		if letter in alphabet:
			s = letter + s
	return s


def reverse_letter(string):
	li = []
	for i in string:
		if i.isalpha():
			li.append(i)
		else:
			pass
	return ''.join(li[::-1])


def reverse_letter(string):
	return ''.join((s for s in string if 97 <= ord(s) <= 122))[::-1]


def reverse_letter(string):
	list = ''
	list1 = list.join([c for c in string if c.isalpha()])
	return list1[::-1]


def reverse_letter(string):
	only_char = ''
	for char in string:
		if char.isalpha():
			only_char += char
	return only_char[::-1]


def reverse_letter(line):
	letters = list(filter(str.isalpha, list(line)))
	letters.reverse()
	return ''.join(letters)


def reverse_letter(string):
	ans = []
	for i in list(string):
		if i.isalpha():
			ans.append(i)
	a = ''.join(ans)[::-1]
	return a


import pandas as pd

def reverse_letter(s):
	return ''.join([i for i in s if i.isalpha()])[::-1]


def reverse_letter(string):
	out = []
	for n in range(len(string)):
		if string[n].isalpha():
			out.insert(0, string[n])
	return ''.join(out)


def reverse_letter(string):
	res = ''.join([a for a in string[::-1] if a.isalpha()])
	return res


def reverse_letter(string):
	result = list(string[::-1])
	answer = []
	for i in result:
		if i.isalpha():
			answer.append(i)
	return ''.join(answer)


def reverse_letter(string):
	lst = ''.join([i for i in string if i.isalpha()])
	rev = lst[::-1]
	return rev


import re

def reverse_letter(string):
	regex = re.compile('[^a-z]')
	reg = regex.sub('', string)
	reverse_word = reg[::-1]
	return reverse_word


import string

def reverse_letter(input_str):
	return ''.join([c for c in input_str if c in string.ascii_letters][::-1])


def reverse_letter(string):
	return ''.join((string[i] if string[i].isalpha() else '' for i in reversed(list(range(len(string))))))


def reverse_letter(string):
	alphabet = 'abcdefghijklmnopqrstuvwxyz'
	reversed_word = list()
	for letter in string:
		if letter in alphabet:
			reversed_word.append(letter)
	reversed_word.reverse()
	return ''.join(reversed_word)


def reverse_letter(string):
	lst = list(string)
	lst.reverse()
	newlst = []
	for item in lst:
		if not item.isalpha():
			pass
		else:
			newlst.append(item)
	return ''.join(newlst)


def reverse_letter(string):
	outputArray = []
	for a in string:
		if a.isalpha():
			outputArray.append(a)
	outputArray.reverse()
	return ''.join(outputArray)


from string import ascii_lowercase

def reverse_letter(string):
	return ''.join((l for l in string[::-1] if l in ascii_lowercase))


def reverse_letter(string):
	alphabet = 'abcdefghijklmnopqrstuvwxyz'
	x = ''
	for letter in string:
		if letter in alphabet:
			x += letter
	return x[::-1]


def reverse_letter(string):
	iaprw = []
	for i in string:
		if i.isalpha() == True:
			iaprw.append(i)
	iaprw.reverse()
	return ''.join(iaprw)


def reverse_letter(string):
	lt = 'qwertyuiopalskjdhfgzxcvbnm'
	s = ''
	for i in string:
		if i in lt:
			s = s + i
	return s[::-1]


def reverse_letter(string):
	s = ''.join(filter(str.isalpha, string))
	inverse = s[::-1]
	return inverse


def reverse_letter(string):
	result = ''.join([i for i in string if not i.isdigit()])
	alphanumeric = ''.join([i for i in result if i.isalnum()])
	return alphanumeric[::-1]


def reverse_letter(string):
	arr = list(string)
	arr2 = []
	for j in range(0, len(arr)):
		if arr[j].isalpha() == True:
			arr2.append(arr[j])
	return ''.join(arr2[::-1])