How to use the dtaidistance.dtw_c function in dtaidistance

import pytest
import numpy as np
import sys, os
sys.path.append(os.path.join(os.path.dirname(os.path.realpath(__file__)), os.pardir))
from dtaidistance import dtw, dtw_c
import logging


logger = logging.getLogger("be.kuleuven.dtai.distance")


if dtw_c is None:
    print('ERROR: dtw_c is not build')
    sys.exit(1)

def test_distance1_a():
    # dist_opts = {'max_dist': 0.201, 'max_step': 0.011, 'max_length_diff': 8, 'window': 3}
    dist_opts = {'window': 3}
    s1 = np.array([ 0., 0.01, 0.,   0.01, 0., 0.,   0.,   0.01, 0.01, 0.02, 0.,  0.])
    s2 = np.array([ 0., 0.02, 0.02, 0.,   0., 0.01, 0.01, 0.,   0.,   0.,   0.])
    d1 = dtw.distance(s1, s2, **dist_opts)
    d2 = dtw_c.distance_nogil(s1, s2, **dist_opts)
    assert d1 == d2
    assert d1 == pytest.approx(0.02)


def test_distance1_b():
    dist_opts = {}

def test_distance2_c():
    dist_opts = {}
    s1 = np.array([0.0, 0.0, 2.0, 1.0, 1.0, 0.0, 0.0])
    s2 = np.array([0.0, 1.0, 1.0, 1.0, 0.0, 0.0, 0.0])
    d1 = dtw.distance(s1, s2, **dist_opts)
    d2 = dtw_c.distance_nogil(s1, s2, **dist_opts)
    assert d1 == d2
    assert d1 == pytest.approx(1.0)

def test_psi_dtw_1c():
    x = np.arange(0, 20, .5)
    s1 = np.sin(x)
    s2 = np.sin(x - 1)
    d = dtw_c.distance_nogil(s1, s2, psi=2)
    np.testing.assert_equal(d, 0.0)

def test_psi_dtw_2c():
    x = np.arange(0, 20, .5)
    s1 = np.sin(x - 1)
    s2 = np.sin(x)
    d = dtw_c.distance_nogil(s1, s2, psi=2, window=3)
    np.testing.assert_equal(d, 0.0)

def test_distance1_c():
    s1 = np.array([0., 0, 1, 2, 1, 0, 1, 0, 0])
    s2 = np.array([0, 1, 2, 0, 0, 0, 0, 0, 0], dtype=np.double)
    d3 = dtw_c.distance(s1, s2)
    assert(d3) == pytest.approx(math.sqrt(2))

def test_distance1_d():
    s1 = np.array([0., 0, 1, 2, 1, 0, 1, 0, 0])
    s2 = np.array([0., 1, 2, 0, 0, 0, 0, 0, 0])
    d = dtw_c.distance_nogil(s1, s2)
    assert(d) == pytest.approx(math.sqrt(2))

def d():
        return dtw_c.distance(s1, s2)

def d():
        return dtw_c.distance_nogil(s1, s2)