Parameters for CreateFishnet

I´m about to create a fishnet. The CreateFishnet tool has several parameters, between them the origin_coord - The starting pivot point of the fishnetl. Data type of this parameter is Point

Now there are several ways to create this point and use it in the CreateFishnet tool.

a) myOrigin = '19273.61 18471.17' - this makes a "tuplet"(right?) of strings

b) myOrigin = str(19273.61) + " " + str(18471.17)

c) myOrigin = '%f %f' %(extent.XMin, extent.YMin)

all this makes a string like "number space number".

But ist this a point parameter? Why do we have to convert a number to string and then back to numbers?

i tried this:

d) myOrigin = [X_m,Y_m] - doesn´t work as parameter in CreateFishnet

e) Origin_m_m = arcpy.Point(X_m,Y_m) - doesn´t work neither

Can somebody explainy, what´s the difference?