Accumulated distance between points

Question

I have this piece of code that I can make lines between points and calculate the length of the line, but now I need to calculate the accumulated distance only between the X axis, I managed to use expressions like p2.x() + p1.x() to calculate this but when I try to put it in a field it says that it is not possible because the type of the variable is float. How could I do this?

iter1 = layer.getFeatures()
for feature1 in iter1:
    p1 = feature1.geometry().asPoint()
    # loop all points again:
    iter2 = layer.getFeatures()
    for feature2 in iter2:
        # following line creates lines from one feature to previous feature:
        if feature2.id() == feature1.id() + 1:
            # create new line feature:
            p2 = feature2.geometry().asPoint()
            l = QgsGeometry.fromPolylineXY([p1,p2])
            linha = QgsFeature()
            linha.setGeometry(l)
            linha.setAttributes([l.length()])
            pr.addFeature(linha)


vl.updateFields()