Override default, adding the capture of content and contenttype.

def from_dict(cls, d):
        """ Override default, adding the capture of content and contenttype.
        """
        o = super(Signature, cls).from_dict(d)
        if 'content' in d:
            # Sometimes, several contents, (one txt, other  html), take last
            try:
                o._content = d['content']['_content']
                o._contenttype = d['content']['type']
            except TypeError:
                o._content = d['content'][-1]['_content']
                o._contenttype = d['content'][-1]['type']

        return o