Hi - During lockdown I have been trying to learn songs (properly) by mapping out the chords/harmony. It's a slow process but it is certainly working. However, I am currently baffled by a chord sequence in the song 'When Sunny Gets Blue'. It's in the 5th bar of the song. The song is in G for me (tenor key). In bar 5 there is a C#7b5 (half dim) chord followed by C-7 (iv-7) F7 (bVII7) and then moving to G major in bar 6. I cannot work out what the function of this C#7b5 is doing in this instance. Apologies if this is really simple and obvious. Any help from you musical wizards out there would be appreciated. Thank you