code: def resname_in_proximity(resname, model, chains, resnums, threshold=5):
      
      residues = [r for r in model.get_residues() if r.get_resname() == resname]
  
      chains = ssbio.utils.force_list(chains)
      resnums = ssbio.utils.force_list(resnums)
  
      for chain in chains:
          for resnum in resnums:
              my_residue_last_atom = model[chain][resnum].child_list[-1]
              for rz in residues:
                  distance = rz.child_list[-1] - my_residue_last_atom
                  if distance < threshold:
                      # print(resnum, rz, distance)
                      return True
  
      return False
docs: Search within the proximity of a defined list of residue numbers and their chains for any specifed residue name.
  
      Args:
          resname (str): Residue name to search for in proximity of specified chains + resnums
          model: Biopython Model object
          chains (str, list): Chain ID or IDs to check
          resnums (int, list): Residue numbers within the chain to check
          threshold (float): Cutoff in Angstroms for returning True if a RESNAME is near
  
      Returns:
          bool: True if a RESNAME is within the threshold cutoff