code: def match_field(self, field, value, required=True, new_group=False):
          
          # If not the start of the query string, add an AND or OR
          if self.initialized:
              if required:
                  self._and_join(new_group)
              else:
                  self._or_join(new_group)
          self._field(field, value)
          return self
docs: Add a ``field:value`` term to the query.
          Matches will have the ``value`` in the ``field``.
  
          Arguments:
              field (str): The field to check for the value.
                      The field must be namespaced according to Elasticsearch rules
                      using the dot syntax.
                      For example, ``"mdf.source_name"`` is the ``source_name`` field
                      of the ``mdf`` dictionary.
              value (str): The value to match.
              required (bool): If ``True``, will add term with ``AND``.
                      If ``False``, will use ``OR``. **Default:** ``True``.
              new_group (bool): If ``True``, will separate the term into a new parenthetical group.
                      If ``False``, will not.
                      **Default:** ``False``.
  
          Returns:
              SearchHelper: Self