Method vs Variable lookup in Ruby

lookup.rb

# Variable before method
a = "A variable"
def a; "A method"; end

puts a # A variable

# Method before variable
def b; "B method"; end
b = "B variable"

puts b # B variable

# Method only
def c; "C method"; end
puts c # C method

# Variable before setter method
d = "d"
# self.d = "self.d =" Cannot call method before definition
def d=(v); puts "d=(#{v})"; end

# Setter method before variable
def e=(v); puts "e=(#{v})"; end
e = "e" # Nothing
self.e = "self.e" # e=(self.e)

output.log

A variable
B variable
C method
e=(self.e)