Parse a YAML specification of a data port into this object.

def parse_yaml(self, y):
        '''Parse a YAML specification of a data port into this object.'''
        self.name = y['name']
        if RTS_EXT_NS_YAML + 'comment' in y:
            self.comment = y[RTS_EXT_NS_YAML + 'comment']
        if RTS_EXT_NS_YAML + 'visible' in y:
            visible = y.get(RTS_EXT_NS_YAML + 'visible')
            if visible == True or visible == 'true' or visible == 'True':
                self.visible = True
            else:
                self.visible = False
        if RTS_EXT_NS_YAML + 'properties' in y:
            for p in y.get(RTS_EXT_NS_YAML + 'properties'):
                if 'value' in p:
                    value = p['value']
                else:
                    value = None
                self._properties[p['name']] = value
        return self