def get_number_observations(self):
        '''
        Returns the number of observations in the data file
        '''
        if isinstance(self.data, dict) and ('exx' in self.data.keys()):
            return len(self.data['exx'])
        else:
            return 0
def get_number_observations ( self ) : if isinstance ( self . data , dict ) and ( 'exx' in self . data . keys ( ) ) : return len ( self . data [ 'exx' ] ) else : return 0
Returns the number of observations in the data file