added import statement to all the examples
added import statement to all the examples

yashu-seth/pgmpy,pgmpy/pgmpy,kris-singh/pgmpy,pgmpy/pgmpy,kris-singh/pgmpy,khalibartan/pgmpy,abinashpanda/pgmpy,anaviltripathi/pgmpy,kislayabhi/pgmpy,palashahuja/pgmpy,pratyakshs/pgmpy,anaviltripathi/pgmpy,palashahuja/pgmpy,vivek425ster/pgmpy,jhonatanoliveira/pgmpy,ankurankan/pgmpy,abinashpanda/pgmpy,vivek425ster/pgmpy,kislayabhi/pgmpy,sandeepkrjha/pgmpy,liquidmetal/pgmpy,jhonatanoliveira/pgmpy,pratyakshs/pgmpy,liquidmetal/pgmpy,ankurankan/pgmpy,sandeepkrjha/pgmpy,khalibartan/pgmpy,yashu-seth/pgmpy