class_docstr: Exponential Distribution 
class_docstr_tok: ["Exponential","Distribution"]
docstr: Returns the log pdf at x 
docstr_tok: ["Returns","the","log","pdf","at","x"]
code: def logp(self, x):
      """Returns the log pdf at x"""
      if x < 0:
          return -np.inf
      return np.log(self.lam) - self.lam * x
  
imports: from __future__ import absolute_import
  from __future__ import division
  import numpy
  from .distribution import Continuous
  from ..exd import domains
label_desc: Use image node_id 4 for calling the Exponential obj's underlying member method code with example usage: obj.logp(x) and returns: unknown, unknown