Chacha20 specifications

[WhiteBowlerHat]

In the pycryptodome/src/chacha20.c file :

In the static int chacha20_core(stream_state *state, uint32_t h[16]) function :

Why does it only makes 10 round ? Shouldn't it be 20 ?
for (i=0; i<10; i++) { <------------------------ HERE
/°° Column round °°/
QR(h[0], h[4], h[ 8], h[12]);
QR(h[1], h[5], h[ 9], h[13]);
QR(h[2], h[6], h[10], h[14]);
QR(h[3], h[7], h[11], h[15]);
/°° Diagonal round °°/
QR(h[0], h[5], h[10], h[15]);
QR(h[1], h[6], h[11], h[12]);
QR(h[2], h[7], h[ 8], h[13]);
QR(h[3], h[4], h[ 9], h[14]);
}

In the D. J. Bernstein website it is specified :
for (i = 20;i > 0;i -= 2) { <--------------------HERE
QUARTERROUND( 0, 4, 8,12)
QUARTERROUND( 1, 5, 9,13)
QUARTERROUND( 2, 6,10,14)
QUARTERROUND( 3, 7,11,15)
QUARTERROUND( 0, 5,10,15)
QUARTERROUND( 1, 6,11,12)
QUARTERROUND( 2, 7, 8,13)
QUARTERROUND( 3, 4, 9,14)
}
https://cr.yp.to/streamciphers/timings/estreambench/submissions/salsa20/chacha20/ref/chacha.c

[WhiteBowlerHat]

I didn't see the -2 decrement