code: def slice_by_coord( self, start, end ):
          
          start_col = self.coord_to_col( start )
          end_col = self.coord_to_col( end )
          if (self.strand == '-'):
              (start_col,end_col) = (end_col,start_col)
          return self.slice( start_col, end_col )
docs: Return the slice of the component corresponding to a coordinate interval.
  
          start and end are relative to the + strand, regardless of the component's strand.