code: def space_name(subject, schema, fractal):
      r"""Get the namespace string.
  
      Parameters
      ----------
      subject : str
          An identifier for a group of related items.
      schema : str
          The data related to the ``subject``.
      fractal : str
          The time fractal of the data, e.g., "5m" or "1d".
  
      Returns
      -------
      name : str
          The joined namespace string.
  
      """
      name = USEP.join([subject, schema, fractal])
      return name
  
imports: from alphapy.globals import USEP
label_desc: Use image node_id 1 for calling a global function with example usage: space_name(subject, schema, fractal) and returns: name