INTEGER, PLUS, MINUS, MULTIPLY, DIVIDE, LPAREN, RPAREN, EOF, OPEN, CLOSE, BANG, ASSIGN, SEMI, ID = (
    'INTEGER',
    'PLUS',
    'MINUS',
    'MULTIPLY',
    'DIVIDE',
    'LPAREN',
    'RPAREN',
    'EOF',
    'OPEN',
    'CLOSE',
    'BANG',
    'ASSIGN',
    'SEMI',
    'ID'
)

ASSIGN   = 'ASSIGN'
BANG     = 'BANG'
CLOSE    = 'CLOSE'
DIVIDE   = 'DIVIDE'
EOF      = 'EOF'
ID       = 'ID'
INTEGER  = 'INTEGER'
LPAREN   = 'LPAREN'
MINUS    = 'MINUS'
MULTIPLY = 'MULTIPLY'
OPEN     = 'OPEN'
PLUS     = 'PLUS'
RPAREN   = 'RPAREN'
SEMI     = 'SEMI'

Fix token names format for readability.