import re


def to_camel_case(string: str) -> str:
    """
    Converts a string from snake_case to camelCase.

    :param string: string in snake_case notation

    :return: `string` converted to camelCase
    """
    if string.find('_') == -1:
        return string
    return re.sub(
        r'(.)(_)(.)',
        lambda m: f'{m.group(1)}{m.group(3).upper()}',
        string.lower().strip('_')
    )