Syntax error in formula from a newbie

if field(‘DiagnosisCode’) == ‘D1234’
‘Chronic Lower Back Pain’
elsif field(‘DiagnosisCode’) == ‘E5678’
‘Type 2 Diabetes Mellitus’
elsif field(‘DiagnosisCode’) == ‘F91011’
‘Essential Hypertension’
elsif field(‘DiagnosisCode’) == ‘G1213’
‘Acute Bronchitis’
elsif field(‘DiagnosisCode’) == ‘H1415’
‘Generalised Anxiety Disorder’
elsif field(‘DiagnosisCode’) == ‘I1617’
‘Iron Deficiency Anaemia’
elsif field(‘DiagnosisCode’) == ‘J1819’
‘Migraine without Aura’
elsif field(‘DiagnosisCode’) == ‘K2021’
‘Hyperlipidemia’
elsif field(‘DiagnosisCode’) == ‘L2223’
‘Chronic Kidney Disease Stage 3’
elsif field(‘DiagnosisCode’) == ‘M2425’
‘Asthma, Unspecified’
else
‘Other Diagnosis’
end
please kindly help