Hash

实例方法：

assert_valid_keys

compact
compact!

deep_dup
deep_merge
deep_merge!

deep_stringify_keys
deep_stringify_keys!

deep_symbolize_keys
deep_symbolize_keys!

deep_transform_keys
deep_transform_keys!

except
except!

extract!

extractable_options?

nested_under_indifferent_access
with_indifferent_access

reverse_merge
reverse_merge! & reverse_update

slice
slice!

stringify_keys
stringify_keys!

symbolize_keys & to_options
symbolize_keys! & to_options!

to_param
to_query

to_xml

transform_keys
transform_keys!

类方法：

from_trusted_xml
from_xml