code: def is_reading_in_conditional_node(self, variable):
          
          variables_read = [n.variables_read for n in self.nodes if n.contains_if()]
          variables_read = [item for sublist in variables_read for item in sublist]
          return variable in variables_read
docs: Check if the function reads the variable in a IF node
          Args:
              variable (Variable):
          Returns:
              bool: True if the variable is read