class SyntaxTree::Parser

def find_token_error(location)

the purpose of locating the error.
Returns the current location that is being looked at for the parser for 
def find_token_error(location)
  if location
    # If we explicitly passed a location into this find_token_error method,
    # that means that's the source of the error, so we'll use that
    # information for our error object.
    lineno = location.start_line
    [lineno, location.start_char - line_counts[lineno - 1].start]
  elsif lineno && column
    # If there is a line number associated with the current ripper state,
    # then we'll use that information to generate the error.
    [lineno, column]
  elsif (location = tokens.last_deleted&.location)
    # If we've already deleted a token from the list of tokens that we are
    # consuming, then we'll fall back to that token's location.
    lineno = location.start_line
    [lineno, location.start_char - line_counts[lineno - 1].start]
  else
    # Finally, it's possible that when we hit this error the parsing thread
    # for ripper has died. In that case, lineno and column both return nil.
    # So we're just going to set it to line 1, column 0 in the hopes that
    # that makes any sense.
    [1, 0]
  end
end