code: def parse_and_load_contexts(contexts, schema=None, werr=False):
      
      ctx = dict()
      diff = None
  
      if contexts:
          for ctx_path, ctx_type in concat(parse_filespec(c) for c in contexts):
              try:
                  diff = load_context(ctx_path, ctx_type, scm=schema)
                  if diff is not None:
                      merge(ctx, diff)
              except (IOError, OSError, AttributeError):
                  if werr:
                      raise
      return ctx
docs: :param contexts: list of context file specs
      :param schema: JSON schema file in any formats anyconfig supports, to
          validate given context files
      :param werr: Exit immediately if True and any errors occurrs
          while loading context files