expirmental expr implementation
pull expr.expr class into default import
made a few changes and clean up code
simplify expr class
update documentation, make modifications
correct docs
correct documentation, add tests
made Field.where a reference to root, correct README example
made README example more pythonic
added more tests, document code
documented cargo.expr module
bump version to reflect changes
optimize code, refactor tests
modify docs
bump version to reflect changes
document field
Merge pull request #3 from eugene-eeo/field-expr

Field expr