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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
 Compute all-to-all connectivity in sensor space
Computes the Phase Lag Index (PLI) between all gradiometers and shows the
connectivity in 3D using the helmet geometry. The left visual stimulation data
are used which produces strong connectvitiy in the right occipital sensors.
Step1:  Set parameters
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Python Code:
# Author: Martin Luessi <mluessi@nmr.mgh.harvard.edu>
#
# License: BSD (3-clause)
import mne
from mne import io
from mne.connectivity import spectral_connectivity
from mne.datasets import sample
from mne.viz import plot_sensors_connectivity
print(__doc__)
Explanation: Compute all-to-all connectivity in sensor space
Computes the Phase Lag Index (PLI) between all gradiometers and shows the
connectivity in 3D using the helmet geometry. The left visual stimulation data
are used which produces strong connectvitiy in the right occipital sensors.
End of explanation
data_path = sample.data_path()
raw_fname = data_path + '/MEG/sample/sample_audvis_filt-0-40_raw.fif'
event_fname = data_path + '/MEG/sample/sample_audvis_filt-0-40_raw-eve.fif'
# Setup for reading the raw data
raw = io.read_raw_fif(raw_fname)
events = mne.read_events(event_fname)
# Add a bad channel
raw.info['bads'] += ['MEG 2443']
# Pick MEG gradiometers
picks = mne.pick_types(raw.info, meg='grad', eeg=False, stim=False, eog=True,
                       exclude='bads')
# Create epochs for the visual condition
event_id, tmin, tmax = 3, -0.2, 1.5  # need a long enough epoch for 5 cycles
epochs = mne.Epochs(raw, events, event_id, tmin, tmax, picks=picks,
                    baseline=(None, 0), reject=dict(grad=4000e-13, eog=150e-6))
# Compute connectivity for band containing the evoked response.
# We exclude the baseline period
fmin, fmax = 3., 9.
sfreq = raw.info['sfreq']  # the sampling frequency
tmin = 0.0  # exclude the baseline period
epochs.load_data().pick_types(meg='grad')  # just keep MEG and no EOG now
con, freqs, times, n_epochs, n_tapers = spectral_connectivity(
    epochs, method='pli', mode='multitaper', sfreq=sfreq, fmin=fmin, fmax=fmax,
    faverage=True, tmin=tmin, mt_adaptive=False, n_jobs=1)
# Now, visualize the connectivity in 3D
plot_sensors_connectivity(epochs.info, con[:, :, 0])
Explanation: Set parameters
End of explanation
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