code: def _all_feature_values(
              self,
              column,
              feature,
              distinct=True,
              contig=None,
              strand=None):
          
          return self.db.query_feature_values(
              column=column,
              feature=feature,
              distinct=distinct,
              contig=contig,
              strand=strand)
docs: Cached lookup of all values for a particular feature property from
          the database, caches repeated queries in memory and
          stores them as a CSV.
  
          Parameters
          ----------
  
          column : str
              Name of property (e.g. exon_id)
  
          feature : str
              Type of entry (e.g. exon)
  
          distinct : bool, optional
              Keep only unique values
  
          contig : str, optional
              Restrict query to particular contig
  
          strand : str, optional
              Restrict results to "+" or "-" strands
  
          Returns a list constructed from query results.