       {
         'match': '<-'
         'name': 'keyword.operator.assignment.stan'
+      }
+      {
+        'match': ':'
+        'name': 'keyword.operator.colon.stan'
       }
       {
         'match': '\\|\\||&&'

    'comment': 'generic variable names'
  }
  {
    'include': '#numbers'
  }
  {
    'include': '#operators'
  }
  {
    'match': ','
    'name': 'meta.delimiter.comma.stan'
  }
  {

    'match': '\\blp__\\b'
    'name': 'invalid.deprecated.lp.stan'
  }
  {
    'include': '#numbers'
    # Needs to go before variable names in order to avoid variables matching
    # the e in real numbers like 12.e34
  }
  {
    'match': '\\b([a-zA-Z0-9_]*__|[0-9_][A-Za-z0-9_]+|_)\\b'
    'name': 'invalid.illegal.variable'
