# File lib/bn4r/bn.rb, line 209
  def get_probability(node_assignment = value, givens_assignments = parents_assignments)
#    raise "Node must have a value and a givens_assignments, otherwise put"   #         + "them in function call" if node_assignment.nil? or givens_assignments.nil?
    # if there's a cached table take the index
    return @table[get_table_index(node_assignment, givens_assignments)] if @table_is_a_proc.nil? or !@table_is_a_proc
    # if the value is calculated on the fly using a function instead of
    # a table
    return @table[node_assignment, givens_assignments]
  end