python - CSV to shapefile missing file

I transform a csv file into a shapefile using the following script:

import shapefile as shp  
import csv            
import tkinter.filedialog   
import urllib.request    
import os 

a = 'csvFiletoTransform.csv'


filename = 'C:/TEMP/ToscaAuxiliar.csv'
urllib.request.urlretrieve(a,filename)    

out_file = tkinter.filedialog.asksaveasfilename()

nombre,codigo,y,x,time=[],[],[],[],[] 



with open('C:/TEMP/xxxx.csv', 'r') as csvfile:
    r = csv.reader(csvfile, delimiter=',')
    for i,row in enumerate(r):
        if i > 0: #skip header
           nombre.append(row[0])
           codigo.append(row[1])
           y.append(float(row[2]))
           x.append(float(row[3]))
           time.append(str(row[4])) 



w = shp.Writer(shp.POINT)
w.autoBalance = 1 #ensures gemoetry and attributes match
w.field('Longitud','F',10,8)
w.field('Latitud','F',10,8)
w.field('Date','D')
w.field('Date / Time','C',50)
w.field('ID','N')


for j,k in enumerate(x):
   w.point(k,y[j]) #write the geometry
   w.record(k,y[j],codigo[j], time[j], nombre[j]) 

os.remove('C:/TEMP/xxxx.csv') 
 w.save(out_file)

it works, but the .prj file is lost.

It creates only the .dbf .shp & .shx files.

How can I do to create the prj file also ?