Positive:
L		expected result: Valid
L+		expected result: Valid
L+4		expected result: Valid
L+34		expected result: Valid
L+4467		expected result: Valid
L24		expected result: Valid
L34553		expected result: Valid
L0		expected result: Valid
L-		expected result: Valid
L-2		expected result: Valid
L-34		expected result: Valid

Negative:
LL		expected result: Invalid
L-0		expected result: Invalid
L+0		expected result: Invalid
L+l		expected result: Invalid
L-l		expected result: Invalid
L-43L		expected result: Invalid
L+35L		expected result: Invalid
L+021		expected result: Invalid
L+023L		expected result: Invalid	
L23l		expected result: Invalid
L-012		expected result: Invalid
L-0L		expected result: Invalid