SFTP in Python? (platform independent)

I’m working on a simple tool that transfers files to a hard-coded location with the password also hard-coded. I’m a python novice, but thanks to ftplib, it was easy:

import ftplib

info= ('someuser', 'password')    #hard-coded

def putfile(file, site, dir, user=(), verbose=True):
    """
    upload a file by ftp to a site/directory
    login hard-coded, binary transfer
    """
    if verbose: print 'Uploading', file
    local = open(file, 'rb')    
    remote = ftplib.FTP(site)   
    remote.login(*user)         
    remote.cwd(dir)
    remote.storbinary('STOR ' + file, local, 1024)
    remote.quit()
    local.close()
    if verbose: print 'Upload done.'

if __name__ == '__main__':
    site="somewhere.com"            #hard-coded
    dir="./uploads/"                #hard-coded
    import sys, getpass
    putfile(sys.argv[1], site, dir, user=info)

The problem is that I can’t find any library that supports sFTP. What’s the normal way to do something like this securely?

Edit: Thanks to the answers here, I’ve gotten it working with Paramiko and this was the syntax.

import paramiko

host = "THEHOST.com"                    #hard-coded
port = 22
transport = paramiko.Transport((host, port))

password = "THEPASSWORD"                #hard-coded
username = "THEUSERNAME"                #hard-coded
transport.connect(username = username, password = password)

sftp = paramiko.SFTPClient.from_transport(transport)

import sys
path="./THETARGETDIRECTORY/" + sys.argv[1]    #hard-coded
localpath = sys.argv[1]
sftp.put(localpath, path)

sftp.close()
transport.close()
print 'Upload done.'

Thanks again!