code: def overlap(self, other: 'Span'):
          
          return not (
              # if one rectangle is left of other
              other.column_end <= self.column_start
              or self.column_end <= other.column_start
              # if one rectangle is above other
              or other.row_end <= self.row_start
              or self.row_end <= other.row_start
          )
docs: Detect if two spans overlap.