def generate(env):
    """Add Builders and construction variables for zip to an Environment."""
    try:
        bld = env['BUILDERS']['Zip']
    except KeyError:
        bld = ZipBuilder
        env['BUILDERS']['Zip'] = bld

    env['ZIP']        = 'zip'
    env['ZIPFLAGS']   = SCons.Util.CLVar('')
    env['ZIPCOM']     = zipAction
    env['ZIPCOMPRESSION'] =  zipcompression
    env['ZIPSUFFIX']  = '.zip'
    env['ZIPROOT']    = SCons.Util.CLVar('')
Add Builders and construction variables for zip to an Environment.