code: def merged_pex(cls, path, pex_info, interpreter, pexes, interpeter_constraints=None):
      
      pex_paths = [pex.path() for pex in pexes if pex]
      if pex_paths:
        pex_info = pex_info.copy()
        pex_info.merge_pex_path(':'.join(pex_paths))
  
      with safe_concurrent_creation(path) as safe_path:
        builder = PEXBuilder(safe_path, interpreter, pex_info=pex_info)
        if interpeter_constraints:
          for constraint in interpeter_constraints:
            builder.add_interpreter_constraint(constraint)
        yield builder
docs: Yields a pex builder at path with the given pexes already merged.
  
      :rtype: :class:`pex.pex_builder.PEXBuilder`