code: def collate(self, merge_type=None, drop=[], drop_constant=False):
          
          from .element import Collator
          merge_type=merge_type if merge_type else self.__class__
          return Collator(self, merge_type=merge_type, drop=drop,
                          drop_constant=drop_constant)()
docs: Collate allows reordering nested containers
  
          Collation allows collapsing nested mapping types by merging
          their dimensions. In simple terms in merges nested containers
          into a single merged type.
  
          In the simple case a HoloMap containing other HoloMaps can
          easily be joined in this way. However collation is
          particularly useful when the objects being joined are deeply
          nested, e.g. you want to join multiple Layouts recorded at
          different times, collation will return one Layout containing
          HoloMaps indexed by Time. Changing the merge_type will allow
          merging the outer Dimension into any other UniformNdMapping
          type.
  
          Args:
              merge_type: Type of the object to merge with
              drop: List of dimensions to drop
              drop_constant: Drop constant dimensions automatically
  
          Returns:
              Collated Layout or HoloMap