code: def is_file(package):
      
      if hasattr(package, "keys"):
          return any(key for key in package.keys() if key in ["file", "path"])
  
      if os.path.exists(str(package)):
          return True
  
      for start in SCHEME_LIST:
          if str(package).startswith(start):
              return True
  
      return False
docs: Determine if a package name is for a File dependency.