# Given a string, return a string where for every
# char in the original, there are two chars.

# double_char('The') → 'TThhee'
# double_char('AAbb') → 'AAAAbbbb'
# double_char('Hi-There') → 'HHii--TThheerree'


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