How to copy values from field to another using arcpy?

Question

Can some one please let me know how I can do simple field calculation like Copying From "A" to "B" in ArcPy?

I have found lots os example on web which they all used extra expression and they were complicated.what I need is simply doing what we can do in ArcMap GUI like

B = !A!

update:

Here is the code I have so far but I am getting error on running this as

NameError: name 'A' is not defined

point_shp = "G:\\Temp\\All_Provinces.shp"
arcpy.AddField_management(point_shp, "B", "TEXT", "", "", "25", "", "NON_NULLABLE", "NON_REQUIRED", "")
arcpy.CalculateField_management(point_shp, "B", "A", "PYTHON_9.3")

Answer 1

I got it, the A must be wrapped like "!A!"

arcpy.CalculateField_management(point_shp, "B","!A!", "PYTHON_9.3")