Splitting pdf based on range of pages
from PyPDF2 import PdfFileReader, PdfFileWriter

path = "in.pdf"
pdf = PdfFileReader(path, "rb")

pdfWriter = PdfFileWriter()

for page in range(329, 346):
    pdfWriter.addPage(pdf.getPage(page))

outputFileName = "Output2.pdf"

with open(outputFileName, 'wb') as out:
    pdfWriter.write(out)

print ("PDF file has been split")

Merging two or more PDFs into one
from PyPDF2 import PdfFileReader, PdfFileMerger

pdfFile1 = PdfFileReader("Output1.pdf")
pdfFile2 = PdfFileReader("Output2.pdf")

output = PdfFileMerger()

output.append(pdfFile1)
output.append(pdfFile2)

with open("final.pdf", "wb") as outputStream:
    output.write(outputStream)