def getSubstitutionElement(self, elt, ps):
nsuri,ncname = _get_element_nsuri_name(elt)<EOL>typecode = GED(nsuri,ncname)<EOL>if typecode is None:<EOL><INDENT>return<EOL><DEDENT>try:<EOL><INDENT>nsuri,ncname = typecode.substitutionGroup<EOL><DEDENT>except (AttributeError, TypeError):<EOL><INDENT>return<EOL><DEDENT>if (ncname == self.pname) and (nsuri == self.nspname or <EOL>(not nsuri and not self.nspname)):<EOL><INDENT>return typecode<EOL><DEDENT>return<EOL>
if elt matches a member of the head substitutionGroup, return 
        the GED typecode representation of the member.

        head -- ElementDeclaration typecode, 
        elt -- the DOM element being parsed
        ps -- ParsedSoap instance