more test coverage

extra.rst

@@ -28,7 +28,7 @@
 >>> add_breathing("ῑ", ROUGH)
 'ῑ̔'
 
->>> from syllabify import syllabify, add_necessary_breathing
+>>> from syllabify import syllabify, add_necessary_breathing, rebreath
 >>> from syllabify import onset, nucleus, coda, onset_nucleus_coda
 
 >>> syllabify('ῑ́̔στην')
@@ -80,6 +80,13 @@ True
 >>> add_necessary_breathing('ῑ̔́στην')
 'ῑ̔́στην'
 
+>>> add_necessary_breathing('ῑ́')
+'ῑ̓́'
+
+>>> rebreath('')
+''
+
+
 >>> from accentuation import recessive, add_accent, syllable_add_accent, PAROXYTONE
 
 >>> syllabify('ῑ̔στην')