Serialize a Python object in SOAP-ENV:Header, make
        sure everything in Header unique (no #href).  Must call
        serialize first to create a document.

        Parameters: 
            pyobjs -- instances to serialize in SOAP Header
            typecode -- default typecode

def serialize_header(self, pyobj, typecode=None, **kw):
        '''Serialize a Python object in SOAP-ENV:Header, make
        sure everything in Header unique (no #href).  Must call
        serialize first to create a document.

        Parameters: 
            pyobjs -- instances to serialize in SOAP Header
            typecode -- default typecode
        '''
        kw['unique'] = True
        soap_env = _reserved_ns['SOAP-ENV']
        #header = self.dom.getElement(soap_env, 'Header')
        header = self._header
        if header is None:
            header = self._header = self.dom.createAppendElement(soap_env, 
                                                                 'Header')

        typecode = getattr(pyobj, 'typecode', typecode)
        if typecode is None:
            raise RuntimeError(
                   'typecode is required to serialize pyobj in header')

        helt = typecode.serialize(header, self, pyobj, **kw)