docs: def render_template(process, template_string, context):
      """Render template using the specified expression engine."""
      from resolwe.flow.managers import manager
  
      # Get the appropriate expression engine. If none is defined, do not evaluate
      # any expressions.
      expression_engine = process.requirements.get('expression-engine', None)
      if not expression_engine:
          return template_string
  
      return manager.get_expression_engine(expression_engine).evaluate_block(template_string, context)