def __common_triplet(input_string, consonants, vowels):
output = consonants<EOL>while len(output) < <NUM_LIT:3>:<EOL><INDENT>try:<EOL><INDENT>output += vowels.pop(<NUM_LIT:0>)<EOL><DEDENT>except IndexError:<EOL><INDENT>output += '<STR_LIT:X>'<EOL><DEDENT><DEDENT>return output[:<NUM_LIT:3>]<EOL>
__common_triplet(input_string, consonants, vowels) -> string