Add TR variable

src/containers/sequences.jl

 module Sequences
 import JuMP: Model
 import ...BuildSequences: @global_model_constructor
-import ...Variables: variables, start_time, duration, VariableType, get_free_variable
+import ...Variables: variables, start_time, duration, VariableType, get_free_variable, TR
 import ...BuildingBlocks: BuildingBlock, to_block
 
 """
@@ -53,6 +53,8 @@ end_time(seq::Sequence, index::Integer, args...) = start_time(seq, index) + end_
 
 duration(seq::Sequence) = end_time(seq, length(seq))
 
+TR(seq::Sequence) = seq.TR
+variables(::Type{<:Sequence}) = [TR]
 
 
 end

src/variables.jl

@@ -5,6 +5,7 @@ import ..Scanners: gradient_strength, slew_rate
 all_variables_symbols = [
     # general
     :duration => (:block, "duration of the building block in ms."),
+    :TR => (:sequence, "Time on which an MRI sequence repeats itself in ms."),
 
     # RF pulse
     :flip_angle => (:pulse, "The flip angle of the RF pulse in degrees"),