class_docstr: Dirichlet distribution, specified by the concentration vector alpha of
  length d. https://en.wikipedia.org/wiki/Dirichlet_distribution
  
  The Dirichlet distribution is defined on the open (d-1)-simplex, which
  means that a sample (or observation) x = (x_0,..., x_{d-1}) must satisfy:
  
  sum_k x_k = 1 and for all k, x_k > 0.
  
  Parameters
  ----------
  alpha
      concentration vector, of shape (..., d)
  
  F
      A module that can either refer to the Symbol API or the NDArray
      API in MXNet
code: def event_dim(self) -> int:
      return 1
  
imports: from typing import List, Optional, Tuple, Type
  import numpy
  from gluonts.core.component import validated
  from gluonts.mx import Tensor
  from gluonts.mx.util import make_nd_diag
  from .distribution import Distribution, _sample_multiple, getF
  from .distribution_output import DistributionOutput
label_desc: Use image node_id 6 for calling the Dirichlet obj's underlying member method code with example usage: obj.event_dim() and returns: int