parameters: (self, field_name)
return_statement: return self._convert_value(value, field_name)
docstring: Small tool to extract the first not nullvalue of a field: its value
          or the ids if this is a relational field.
docstring_summary: Small tool to extract the first not nullvalue of a field: its value
          or the ids if this is a relational field.
docstring_tokens: Small tool to extract the first not nullvalue of a field : its value or the ids if this is a relational field .
function: def _find_first_notnull(self, field_name):
          """ Small tool to extract the first not nullvalue of a field: its value
          or the ids if this is a relational field. """
          value = next((reg[field_name] for reg in self if reg[field_name]), False)
          return self._convert_value(value, field_name)
function_tokens: def _find_first_notnull ( self , field_name ) : value = next ( ( reg [ field_name ] for reg in self if reg [ field_name ] ) , False ) return self . _convert_value ( value , field_name )