'A higher-level interface to getfirstmatchingheader().
Return a string containing the literal text of the header but with the
keyword stripped.  All leading, trailing and embedded whitespace is
kept in the string, however.  Return None if the header does not
occur.'

def getrawheader(self, name):

    lst = self.getfirstmatchingheader(name)
    if (not lst):
        return None
    lst[0] = lst[0][(len(name) + 1):]
    return ''.join(lst)
