notes

## Avoid using positional arguments
Force users to explicitly use keyword arguments in favor of positional
arguments by using the * argument to delineate positional (one or two)
arguments from the keyword-only arguments.

Whenever confusion may arise, use keyword-only arguments. However,
occasionally positional arguments are okay, such as plot(x,y), but then
an optional axis argument should be a keyword-only argument, like so:

def plot(x, y, *, ax=None, color=None):
    pass

## Use None for default parameter values, unless None is a desired value
Instead of assigning defaults in the function definition like so

def do_something(foo, bar=5):
    pass

rather use None and then describe the defaults in the docstring:

def do_something(foo, bar=None):
    """Function description.

    Parameters
    ----------
    foo: type
        Description of foo.
    bar: type, optional
        Description of bar. Default is 5.
    """
    # assign default values:
    if bar is None:
        bar = 5

## Try to limit lines to 72 chars, and no more than 80 chars.

## Take note: support of a single spike (binned vs unbinned).
If we have a spiketrain, and we slice a single spike from it like so:
st[5] then (at least for now, before making slicng consistent on epochs
instead of on spikes) we have a <spiketrain with 1 spike> object, with
zero support (infinitessimally small). However, we can still bin such a
spiketrain with BinnedSpikeTrain(st[5]) which then returns a
BinnedSpikeTrain object with a single bin, with support duration equal to
the bin width.