code: def melt(ndf: pd.DataFrame, node: Union[str, int]) -> str:
      """Reduces node if in cluster store, otherwise passes it through.
      ex:
  
          node = "4" will take any sequence from get_cluster_store_keys, "1 2 3", "4 3 6" and returns "1 2 3 4 6"
          when they have a common entry (3).
  
      :param ndf, node DataFrame
      :param node: node to melt
      :returns new_parent_name of super node
  
      """
      rdf = ndf[get_cluster_store_keys(ndf, node)]
      topkey = wrap_key(node)
      if not rdf.empty:
          for key in rdf[
              COLLAPSE_NODE
          ].values:  # all these are already wrapped
              # add the keys to cluster
              topkey += f" {key}"  # keep whitespace
          topkey = reduce_key(topkey)
      return topkey
  
imports: from typing import Union, Optional, List
  import copy, logging, pandas, numpy
  from graphistry.PlotterBase import Plottable
label_desc: Use image node_id 11 for calling a global function with example usage: melt(ndf, node) and returns: topkey