def get_param(node, pname):
  """ retrieve the str representation of a parameter from:
    <parameter name="pname"> str_rep </parameter>

  Args:
    node (lxml.etree._Element): xml node with <parameter>.
    pname (str): name of parameter
  Return:
    str: string representation of the parameter value
  """
  pnode = node.find('.//parameter[@name="%s"]' % pname)
  return pnode.text