Function present_mode_from_env 

pub fn present_mode_from_env() -> Option<PresentMode>

Obtains a wgpu::PresentMode from the current environment configuration, if set.

The value returned by this function can be changed by setting the ICED_PRESENT_MODE env variable. The possible values are:

• vsync → wgpu::PresentMode::AutoVsync
• no_vsync → wgpu::PresentMode::AutoNoVsync
• immediate → wgpu::PresentMode::Immediate
• fifo → wgpu::PresentMode::Fifo
• fifo_relaxed → wgpu::PresentMode::FifoRelaxed
• mailbox → wgpu::PresentMode::Mailbox