def check_signature (sig_filename, reject, data_filename="", keyrings=None, autofetch=None):
"""Check the signature of a file and return the fingerprint if the
signature is valid or 'None' if it's not. The first argument is the
def check_signature (sig_filename, reject, data_filename="", keyrings=None, autofetch=None):
"""Check the signature of a file and return the fingerprint if the
signature is valid or 'None' if it's not. The first argument is the