'Constructor.
Args:
alpha: a float32 scalar tensor between 0 and 1 representing interpolation
weight
bootstrap_type: set to either \'hard\' or \'soft\' (default)
anchorwise_output: Outputs loss per anchor. (default False)
Raises:
ValueError: if bootstrap_type is not either \'hard\' or \'soft\''

def __init__(self, alpha, bootstrap_type='soft', anchorwise_output=False):

    if ((bootstrap_type != 'hard') and (bootstrap_type != 'soft')):
        raise ValueError("Unrecognized    bootstrap_type:    must    be    one    of    'hard'    or    'soft.'")
    self._alpha = alpha
    self._bootstrap_type = bootstrap_type
    self._anchorwise_output = anchorwise_output
