What is falsey in multiple assignment?

masgn-conditional.rb

'truthy' if (a, b = [])              # => "truthy"
'truthy' if (a, b = nil)             # => nil
'truthy' if (a, b = [nil])           # => "truthy"
'truthy' if (a, b = [nil, nil])      # => "truthy"
'truthy' if (a, b = [false])         # => "truthy"
'truthy' if (a, b = [false, false])  # => "truthy"
'truthy' if (a, b = [true, false])   # => "truthy"
'truthy' if (a, b = [false, true])   # => "truthy"
'truthy' if (a, b = *[])             # => "truthy"
'truthy' if (a, b = *nil)            # => "truthy"
'truthy' if (a, b = *[nil])          # => "truthy"
'truthy' if (a, b = *[nil, nil])     # => "truthy"
'truthy' if (a, b = *[false])        # => "truthy"
'truthy' if (a, b = *[false, false]) # => "truthy"
'truthy' if (a, b = *[true, false])  # => "truthy"
'truthy' if (a, b = *[false, true])  # => "truthy"