def p_assignation(p):
'''assignation : register S_EQUAL expression S_SEMICOLON'''
node_index = inc()
dot.node(node_index, '=')
dot.edge(node_index, p[1].node_index)
dot.edge(node_index, p[3].node_index)
p[0] = Instructions.Assignation(node_index, p[1], p[3])
p[0].lineno = p[1].lineno
