Sublime Text Plugin - format

BracketFormatterCommand (part 1).py

import sublime
import sublime_plugin

def format(input):
    output = ""
    counter = 0
    SPACE = '  '
    for char in input:
        if char in "([{":
            counter += 1
            output += char + '\n' + SPACE * counter
        elif char in ")]}":
            counter -= 1
            output += '\n' + SPACE * counter + char
        elif char == ',':
            output += char + '\n' + SPACE * counter
        elif char not in ' \n':
            output += char
    return output

class ExampleCommand(sublime_plugin.TextCommand):
    ...