import hashlib


def sha1_string(text):
    """
    Calculate the SHA-1 checksum of a string

    Parameters
    ----------
    text : str
        The string to be checksummed

    Returns
    -------
    hexdigest : str
        The SHA-1 has of the string
    """

    sha = hashlib.sha1()
    sha.update(text)
    return sha.hexdigest()