How do you suppress output in IPython Notebook?

Add %%capture as the first line of the cell. eg

%%capture
print('Hello')
MyFunction()

This simply discards the output, but the %%capture magic can be used to save the output to a variable - consult the docs

Suppress output

Put a ; at the end of a line to suppress the printing of output [Reference].

(credit: https://stackoverflow.com/a/23611571/389812)

You could use io.capture_output:

from IPython.utils import io

with io.capture_output() as captured:
    MyFunction()

to supress (e.g. capture) stdout and stderr for those lines within the with-statement.