code: def letter_combinations(digits):
      if digits == "":
          return []
      kmaps = {
          "2": "abc",
          "3": "def",
          "4": "ghi",
          "5": "jkl",
          "6": "mno",
          "7": "pqrs",
          "8": "tuv",
          "9": "wxyz",
      }
      ans = [""]
      for num in digits:
          tmp = []
          for an in ans:
              for char in kmaps[num]:
                  tmp.append(an + char)
          ans = tmp
      return ans
  
label_desc: Use image node_id 1 for calling a global function with example usage: letter_combinations(digits) and returns: ans, list