<SYSTEM_TASK:>
Given the following text description, write Python code to implement the functionality described below step by step
<END_TASK>
<USER_TASK:>
Description:
 Simple IO
<hr style="border-top-width
Step1:  We now define a function that will create a histogram, fill it and write it to a file. Later, we will read back the histogram from disk.
Step2:  All objects the class of which has a dictionary can be written on disk. By default, the most widely used ROOT classes are shipped with a dictionary
Step3:  Before reading the object, we can check from the commandline the content of the file with the rootls utility
Step4:  We see that the file contains one object of type TH1F, the name of which is theHisto and the title of which is My Test Histogram. 
Let's now use the ROOT interface to read it and draw it
<ASSISTANT_TASK:>
Python Code:
import ROOT
%jsroot on
Explanation: Simple IO
<hr style="border-top-width: 4px; border-top-color: #34609b;">
This simple ROOTbook shows how to create a histogram, fill it and write it.
End of explanation
def writeHisto(outputFileName):
    outputFile = ROOT.TFile(outputFileName, "RECREATE")
    h = ROOT.TH1F("theHisto","My Test Histogram;X Title; Y Title",64, -4, 4)
    h.FillRandom("gaus")
    # now we write to the file
    h.Write()
Explanation: We now define a function that will create a histogram, fill it and write it to a file. Later, we will read back the histogram from disk.
End of explanation
writeHisto("output.root")
Explanation: All objects the class of which has a dictionary can be written on disk. By default, the most widely used ROOT classes are shipped with a dictionary: the histogram is one of those.
Writing on a file is as simple as invoking the Write method.
Now we invoke the function:
End of explanation
%%bash
rootls -l output.root
Explanation: Before reading the object, we can check from the commandline the content of the file with the rootls utility:
End of explanation
inputFile = ROOT.TFile("output.root")
h = inputFile.theHisto
c = ROOT.TCanvas()
h.Draw()
c.Draw()
Explanation: We see that the file contains one object of type TH1F, the name of which is theHisto and the title of which is My Test Histogram. 
Let's now use the ROOT interface to read it and draw it:
End of explanation
<END_TASK>