code: def _parse_source_interface(self, config):
          
          match = re.search(r'vxlan source-interface ([^\s]+)', config)
          value = match.group(1) if match else self.DEFAULT_SRC_INTF
          return dict(source_interface=value)
docs: Parses the conf block and returns the vxlan source-interface value
  
          Parses the provided configuration block and returns the value of
          vxlan source-interface.  If the value is not configured, this method
          will return DEFAULT_SRC_INTF instead.
  
          Args:
              config (str): The Vxlan config block to scan
  
          Return:
              dict: A dict object intended to be merged into the resource dict