'Create new MapreduceSpec.
Args:
name: The name of this mapreduce job type.
mapreduce_id: ID of the mapreduce.
mapper_spec: JSON-encoded string containing a MapperSpec.
params: dictionary of additional mapreduce parameters.
Properties:
name: The name of this mapreduce job type.
mapreduce_id: unique id of this mapreduce as string.
mapper: This MapreduceSpec\'s instance of MapperSpec.
params: dictionary of additional mapreduce parameters.'

def __init__(self, name, mapreduce_id, mapper_spec, params={}):

    self.name = name
    self.mapreduce_id = mapreduce_id
    self.mapper = MapperSpec.from_json(mapper_spec)
    self.params = params
