class_docstr: Inverse Gamma Distribution
  ----
  This class contains methods relating to the inverse gamma distribution for time series.
docstr: Log PDF for Inverse Gamma prior
  
  Parameters
  ----------
  x : float
      Latent variable for which the prior is being formed over
  
  Returns
  ----------
  - log(p(x))
code: def logpdf(self, x):
      """
      Log PDF for Inverse Gamma prior
  
      Parameters
      ----------
      x : float
          Latent variable for which the prior is being formed over
  
      Returns
      ----------
      - log(p(x))
      """
      if self.transform is not None:
          x = self.transform(x)
      return (-self.alpha - 1) * np.log(x) - (self.beta / float(x))
  
file_path: pyflux/pyflux/families/inverse_gamma.py
imports: import numpy
  import scipy.stats
  import scipy.special
  from .family import Family
label_desc: Use image node_id 2 for calling the InverseGamma obj's underlying member method code with example usage: obj.logpdf(x) and returns: unknown