Given a string, you have to return a string in which each character (case-sensitive) is repeated once.

```python
double_char("String") ==> "SSttrriinngg"

double_char("Hello World") ==> "HHeelllloo  WWoorrlldd"

double_char("1234!_ ") ==> "11223344!!__  "
```
Good Luck!

Difficulty: introductory

Starter code:

def double_char(s):
	

Solutions:
def double_char(s):
    return ''.join(c * 2 for c in s)

def double_char(s):
    res = ''
    for i in s:
        res += i*2
    return res

def double_char(s):
    return ''.join(2 * c for c in s)

def double_char(str):
    return "".join(ch+ch for ch in str)


def double_char(str):
    return "".join(c*2 for c in str)

def double_char(s):
    return ''.join(char * 2 for char in s)

def double_char(s):
    y = list(s) # Breaks the string into individual letters
    length = len(y) # Length of string
    ffs = list(range(0,length)) # Creates an array beginning with 0, going up in ones, the length of the original string
    blank="" # Blank string to build from
    for i in ffs: # For (i)tems in ffs, number 0 thru x (length)
        blank = blank + y[i] + y[i] # Essentially blank + list(0) + list(0), then blank + list(1) + list(1)
    return blank

double_char = lambda s: ''.join(a*2 for a in s)

double_char=lambda s:''.join(c+c for c in s)

def double_char(s):
    result = ""
    for i in s:
       result += i + i
    return result


def double_char(s):
    return ''.join([x*2 for x in s])

def double_char(s):
    return ''.join(a*2 for a in s)

OUTPUT = '{0}{0}'.format


def double_char(s):
    return ''.join(OUTPUT(a) for a in s)


def double_char(s):
    result = ''
    for char in s:
        result += char * 2
    return result


def double_char(s):
    slowo = ""   # defining new empty string for doubled word
    for char in s:      # loop going by every char in word s
        char = 2 * char     # for every char doubling it
        slowo += char   # adding doubled char to new string
    return slowo 

def double_char(s):
    answer = []
    for i in s:
        answer.append(i)
        answer.append(i)
    return "".join(answer)

def double_char(s: str) -> str:
    """ Get a string in which each character is repeated once. """
    return "".join(list(map(lambda _: _ * 2, "|".join(s).split("|"))))

def double_char(s):
    new=str()
    for i in s:
       new+=i+i
    pass
    return new

def double_char(some_text):
    return ''.join([2 * letter for letter in some_text])

def double_char(s):
    return ''.join([2*i for i in s])


def double_char(s):
    new_s = ""
    for c in s:
        new_s = "%s%c%c" % (new_s, c, c);
    return new_s

def double_char(s):
    s=list(s)
    lists=[]
    for i in range(len(s)):
        lists.append(s[i]*2)
    string=''
    for i in range(len(lists)):
        string=string+lists[i]
    return string


def addition(char):
    return 2*char

def double_char(s):
    result = list(map(addition, s))
    return ''.join(result)

def double_char(s):
    return ''.join(map(lambda x:''.join(x), zip(s,s)))

def double_char(s):
    return(''.join([s[i]*2 for i in range(len(s))]))

def double_char(s):
    return reduce(lambda x,y: x+y, map(lambda x : 2*x, s))

double_char = lambda s: ''.join([i*2 for i in s])

def double_char(s):
    new_list = []
    for x in s:
        new_list.append(x)
        new_list.append(x)
    return ''.join(new_list)

def double_char(s):
    new = ""
    for char in s:
        new += char * 2
    
    return new

def double_char(s):
    
        return ''.join([character+character for character in s])


def double_char(s):
    z = ""
    for i in range(len(s)):
        z += (s[i])
        z += (s[i])
    return z


def double_char(s):
    total = ""
    for i in s:
        total += i
        total += i
    return total


def double_char(s):
    rtrn = ''
    for x in s:
        rtrn += x*2
    return rtrn

def double_char(s):
    res = ''
    for t in range(len(s)):
        res += 2*s[t]
    return res

def double_char(s):
    res = ""
    for l in s:
        res += l+l
    return res

def double_char(s):
    new_string = ""
    for char in s:
        char = char*2
        new_string += char 
    return new_string

def double_char(s):
    result = ''
    for sym in s:
        result += 2 * sym
    return result

def double_char(s):
    storage=""
    for i in s:
        storage+=i*2
    return storage

def double_char(string):
    fin = ""
    for char in string:
        fin += char * 2
    return fin

def double_char(s):
    output = ""
    for character in s:
        output += 2 * character
    return output

def double_char(s):
    a = [i*2 for i in s]
    return "".join(i for i in a)

def double_char(s):
    array = list(s)
    count = len(array)-1
    while count >= 0:
        array.insert(count, array[count])
        count += -1
    return "".join(array)
        


def double_char(s):
    lst = list(s)
    res = ''
    for el in lst:
        res += el * 2
    return res

def double_char(s):
    n = len(s)
    result = ""
    for i in range(n):
        result += s[i] * 2
    
    return result

def double_char(s):
    r = ''
    for x in s:
        r += 2 * x
    return r

def double_char(s):
    new_string = []
    for i in list(s):
        new_string.append(i+i)
    return "".join(new_string)

def double_char(s):
    tustik=[i*2 for i in s]   
    return ''.join(tustik)    

def double_char(s):
    sss = ''
    for i in s:
        sss += i + i
    return sss

def double_char(s):
    Liste = []
    for i in s:
        Liste.append(i*2)
    return ''.join(Liste)

def double_char(s):
    return_string = ""
    
    for i in s:
        return_string += i * 2
    
    return return_string

def double_char(s):
    return_string = ""
    
    for i in s:
        return_string += i
        return_string += i
    
    return return_string

def double_char(s):
    s = [i+i for i in s]
    return ''.join(s)

def double_char(s):
    my_list = ""
    for i in range(len(list(s))):
        my_list += str(list(s)[i]*2)
    return my_list


def double_char(s):
    hold = ""
    for x in range(len(s)):
        hold += (s[x] * 2)
    return hold


def double_char(s):
    str=''
    for i in s:
        str+=2*i
    return str

def double_char(s):
    dbl = ''
    for i in range(len(s)):
        dbl=dbl+s[i]+s[i]
    return dbl

def double_char(s):
    l = list(s)
    res = []
    for letter in l:
        res.append(letter)
        res.append(letter)
    return "".join(res)

def double_char(s):
    chars = []
    
    for char in s:
        chars.append(char)
        
    for i in range(len(chars)):
        chars[i] = chars[i] * 2
    
    return ''.join(chars)

def double_char(s):
    return ''.join([next_str + next_str for next_str in s])

def double_char(s):
    ans = []
    for i in s:
        a = i * 2
        ans.append(a)
    return "".join(ans)

def double_char(s):
    str=""
    for i in s:
        i*=2
        str+=i
    return str

def double_char(s):
    s2=""
    for i in range(len(s)):
        s2+=2*s[i]
    return s2

def double_char(s):
    return ''.join(['{}'.format(i[0]+i[1]) for i in zip(s,s)])

def double_char(s):
    return ''.join([2*letter for letter in s])

def double_char(s):
    return ''.join([''.join([r,r]) for r in s])

def double_char(s):
    lst=[]
    for x in s:
        lst.append(x)
        lst.append(x)
    lst = "".join(lst)
    return lst

def double_char(s):
    ans = ''
    for i in s:
        ans = ans + i * 2
    return ans

def double_char(s):
    derp = ""
    
    for letters in s:
        derp+=letters + letters
        
    return derp

def double_char(s):
    return "".join([s[x]*2 for x in range(len(s))])

def double_char(s):
    word = ""
    for char in s:
        char = char * 2
        word += char
    return word



def double_char(s):
    res = ''
    for i in s:
        res += f"{i}{i}"
    return res

def double_char(s):
    l = list(s)
    r = []
    for i in range(len(l)):
        r.append(l[i]+l[i])
    return ''.join(r)
    
    


def double_char(s):
    t = ''
    for x in s:
        t += x + x
    return t

def double_char(s):
    double = ""
    for i in range(len(s)):
        double += "{}".format(s[i]*2)
    return double
double_char("String")

def double_char(s):
    x = []
    for i in range(len(s)):
        x.append(2*s[i])
    return ''.join(x)

def double_char(s):
    t = ""
    for x in s:
        t += x*2
    return t

def double_char(s):
    double_s = ''
    for i, x in enumerate(s):
        double_s += (x * 2)
    return double_s

def double_char(s):
    k = list(s)
    arr = []
    for i in range(len(s)):
        arr.append(s[i])
        arr.append(s[i])
    return ''.join(arr)

def double_char(s):
    s = [lett*2 for lett in s]
    y = ''
    x = 0
    while x < len(s):
        y += s[x]
        x +=1 
    return y

def double_char(s):
    s = list(s)
    returnArr = []
    for i in range(len(s)):
        returnArr.append(s[i])
        returnArr.append(s[i])
    return "".join(returnArr)

def double_char(s):
    
    #start with an empty string
    x = ""
    
    ##loop across string s, and add each letter twice to empty string x
    for i in range(len(s)):
        x = x+s[i]+s[i]
    return x

    pass

def double_char(s):
    lisp = ""
    for char in s:
        lisp = lisp + char + char
    return lisp

def double_char(s):
    ans = []
    for i in s:
        ans.append(i*2)
    return "".join(ans)

def double_char(s):
    duplicados = ''
    for char in s:
        duplicados=duplicados+char+char
    return duplicados

def double_char(s):
    final_str = ""
    for i in s:
        final_str += i * 2
    return final_str

def double_char(s):
    return ''.join(list(char*2 for char in s))

def double_char(s):
    
    returnString = ""
    i = 0
    
    while i < len(s):
        returnString = returnString + s[i] + s[i]
        i+= 1
    
    return returnString

def double_char(s):
    return "".join([2*word for word in list(s)])

def double_char(s):
    new_string = ''
    for c in s:
        new_string = new_string + c + c
    return new_string
        


def double_char(s):
    return ''.join(''.join(i) for i in zip(s, s))


def double_char(s):
    final_str = ""
    for char in s:
        final_str += (char + char)
    return final_str


def double_char(s):
    new_str = ''
    for i in s:
        new_str = new_str + i + i
    return new_str

def double_char(s):
    solution = ''
    for char in s:
        solution += char * 2
    return solution

def double_char(s):
    res = map(lambda x: x *2, s)
    res = ''.join(res)
    return res

def double_char(s):
    return "".join(map(lambda i: i+i, s))

from itertools import repeat

def double_char(s):
    return ''.join([x for item in s for x in repeat(item, 2)])

def double_char(s):
    a=""
    for i in s:
        i=i*2
        a+=i
    return a   

def double_char(s):
    x = ''
    return x.join(i * 2 for i in s)

def double_char(s):
    aç = ""
    for a in s:
        aç += a*2
    return aç

def double_char(s):
    return ''.join(x * 2 for x in list(s[:]))