def __init__(self, data, keyrings, require_signature=True, gpg="/usr/bin/gpg"):
"""
@param data: string containing the message
- @param keyrings: seqeuence of keyrings
+ @param keyrings: sequence of keyrings
@param require_signature: if True (the default), will raise an exception if no valid signature was found
@param gpg: location of the gpg binary
"""