code: def regex_findall_variables(content):
      
      try:
          vars_list = []
          for var_tuple in variable_regex_compile.findall(content):
              vars_list.append(
                  var_tuple[0] or var_tuple[1]
              )
          return vars_list
      except TypeError:
          return []
docs: extract all variable names from content, which is in format $variable
  
      Args:
          content (str): string content
  
      Returns:
          list: variables list extracted from string content
  
      Examples:
          >>> regex_findall_variables("$variable")
          ["variable"]
  
          >>> regex_findall_variables("/blog/$postid")
          ["postid"]
  
          >>> regex_findall_variables("/$var1/$var2")
          ["var1", "var2"]
  
          >>> regex_findall_variables("abc")
          []