class_docstr: The class implements Infinite Gaussian Mixture model
  or Dirichlet Process Mixture model.
  This is simply a generalization of Bayesian Gaussian Mixture Models
  with an unknown number of classes.
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docstr: Set the null and prior densities as constant
  (assuming a compact domain)
  
  Parameters
  ----------
  prior_dens: float, optional
              constant for the prior density
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code: def set_constant_densities(self, prior_dens=None):
      """Set the null and prior densities as constant
      (assuming a compact domain)
  
      Parameters
      ----------
      prior_dens: float, optional
                  constant for the prior density
      """
      self.prior_dens = prior_dens
  
imports: import math
  import numpy
  from scipy.special import gammaln
  from .bgmm import BGMM, detsh
label_desc: Use image node_id 3 for calling the IMM obj's underlying member method code with example usage: obj.set_constant_densities(prior_dens) without return types