code: function help (argv, callback) {
    var ret = 'rdf help\n'
    ret += 'commands\n'
    ret += '  rdf cat <uri>                    - displays a uri\n'
    ret += '  rdf cp <source> <dest>           - copies from source to dest uris\n'
    ret += '  rdf help                         - shows help message\n'
    ret += '  rdf ls <uri>                     - shows files in a container\n'
    ret += '  rdf mv <source> <dest>           - moves from source to dest uris\n'
    ret += '  rdf obj <uri> [value]            - watches the first found object\n'
    ret += '  rdf patch <uri> <data>           - patch turtle data to a file\n'
    ret += '  rdf post <uri> <data>            - posts turtle data to a file\n'
    ret += '  rdf put <uri> <data>             - puts turtle data to a file\n'
    ret += '  rdf rm <uri>                     - removes a uri\n'
    ret += '  rdf sub <uri>                    - subscribes to a uri\n'
    ret += '  rdf tail <uri>                   - watches a URI for changes\n'
    ret += '  rdf touch <uri>                  - touches a uri\n'
    ret += '  rdf ws <uri>                     - tests websocket to a uri\n'
    callback(null, ret)
  }
docs: help message
  @param  {array}   argv      arguments
  @param  {Function} callback callback