If

With if and else keywords the flow of a program can be controlled.

if (a.type() == "STRING")
puts("is a string")
else
puts("is not a string")
end

Output

is a string

Elif

elif allows providing of an additional consequence check after if and before evaluating the alternative provided by else. There is no limit on how many elif statements can be used.

if (a.type() == "BOOLEAN")
puts("is a boolean")
elif (a.type() == "STRING")
puts("is a string")
else
puts("i have no idea")

Output

is a string