code: def convert_coerce_type_and_add_to_where_block(coerce_type_block, where_block):
      
      instanceof_filter = convert_coerce_type_to_instanceof_filter(coerce_type_block)
  
      if where_block:
          # There was already a Filter block -- we'll merge the two predicates together.
          return Filter(BinaryComposition(u'&&', instanceof_filter.predicate, where_block.predicate))
      else:
          return instanceof_filter
docs: Create an "INSTANCEOF" Filter from a CoerceType, adding to an existing Filter if any.