code: def parse_file_provider(uri):
      
      providers = {'gs': job_model.P_GCS, 'file': job_model.P_LOCAL}
      # URI scheme detector uses a range up to 30 since none of the IANA
      # registered schemes are longer than this.
      provider_found = re.match(r'^([A-Za-z][A-Za-z0-9+.-]{0,29})://', uri)
      if provider_found:
        prefix = provider_found.group(1).lower()
      else:
        # If no provider is specified in the URI, assume that the local
        # filesystem is being used. Availability and validity of the local
        # file/directory will be checked later.
        prefix = 'file'
      if prefix in providers:
        return providers[prefix]
      else:
        raise ValueError('File prefix not supported: %s://' % prefix)
docs: Find the file provider for a URI.