docs: def convert_trunc(trunc):
      """Convert BEL1 trunc() to BEL2 var()"""
  
      parent_fn_name = trunc.parent_function.name_short
      prefix_list = {"p": "p.", "r": "r.", "g": "c."}
      prefix = prefix_list[parent_fn_name]
  
      new_var_arg = f'"truncated at {trunc.args[0].value}"'
  
      new_var = bel.lang.ast.Function("var", bo.spec)
  
      new_var.add_argument(StrArg(new_var_arg, new_var))
  
      return new_var