'Constructs a VGSLSpecs.
Args:
widths:  Tensor of size batch_size of the widths of the inputs.
heights: Tensor of size batch_size of the heights of the inputs.
is_training: True if the graph should be build for training.'

def __init__(self, widths, heights, is_training):

    self.model_str = None
    self.is_training = is_training
    self.widths = widths
    self.heights = heights
    self.reduction_factors = [1.0, 1.0, 1.0, 1.0]
    self.valid_ops = [self.AddSeries, self.AddParallel, self.AddConvLayer, self.AddMaxPool, self.AddDropout, self.AddReShape, self.AddFCLayer, self.AddLSTMLayer]
    self.transtab = maketrans('(,)', '___')
