Merge branch 'fix_20' into 'master'

Fix 20

Closes #23

See merge request !22
4 jobs for master in 6 minutes and 59 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Test
passed #71996
test:python3.5-stretch-pyqt5_larch

00:03:36

passed #71995
test:python3.5-stretch-pyqt5_pymca

00:06:03

passed #71997
test:python3.5-stretch-pyqt5_pymca_larch

00:06:50

passed #71998
test:test-est-tutorials_pymca

00:03:19