code: def is_r_script(opspec):
      return os.path.isfile(opspec) and opspec[-2:].upper() == ".R"
  
file_path: guildai/guild/plugins/r_util.py
imports: import os
  import re
  import subprocess
  from guild import util
label_desc: Use image node_id 1 for calling a global function with example usage: is_r_script(opspec) and returns: unknown