import re


def is_valid_input(service_name):
    """
    Validate the input.

    Args:
        service_name (str): the name of the service. given as an argument to the module

    Returns:
        bool: True if the input is valid, else False.
    """
    if re.match("^[A-Za-z0_]*$", service_name):
        return True
    return False