class ActiveSupport::HashWithIndifferentAccess

def []=(key, value)

Experimental RBS support (using type sampling data from the type_fusion project). 

def []=: (String key, String value) -> untyped

This signature was generated using 1 sample from 1 application.

This value can be later fetched using either +:key+ or 'key'.

hash[:key] = 'value'
hash = ActiveSupport::HashWithIndifferentAccess.new

Assigns a new value to the hash: 
def []=(key, value)
  regular_writer(convert_key(key), convert_value(value, conversion: :assignment))
end