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


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

