ignoring linespace and count line

def countLine():
        fileName='file'
        f=open(fileName)
        count = 0
        for i in f:
                if i.strip() != "":
                        count = count + 1

        f.close()
        return count

count line including linespace

def checkFile():
    f=open("./file")
    a=0
    for line in f:
            a = a + 1
    f.close()
    return a

count line without linespace

def countLineInFile():
    f=open('./filename.txt')
    line = f.readline()
    lineNumber = 0
   while line != "":
        line = f.readline()
        lineNumber = lineNumber + 1

    f.close()

    return lineNumber