[Mne_analysis] Number of components to use in CSP

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Hi all,
How to define  "n_components" in the following function:
mne.decoding.CSP(n_components=4, reg=None, log=None, cov_est='concat',
transform_into='average_power', norm_trace=False,
cov_method_params=None, rank=None)

Is it dependent on the number of classes i have?
can i have it to be more than 4? for example 25?
Is is dependent on the number of electrodes (channels) i have?

many thanks in advance for your help