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Short helpfile for action UPPER_WALLS
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The following arguments are compulsory: 

                     AT - the positions of the wall. The a_i in the expression for a 
                          wall. 
                  KAPPA - the force constant for the wall. The k_i in the expression 
                          for a wall. 
                 OFFSET - ( default=0.0 ) the offset for the start of the wall. The 
                          o_i in the expression for a wall. 
                    EXP - ( default=2.0 ) the powers for the walls. The e_i in the 
                          expression for a wall. 
                    EPS - ( default=1.0 ) the values for s_i in the expression for a 
                          wall 
                    ARG - the arguments on which the bias is acting. You can use 
                          multiple instances of this keyword i.e. ARG1, ARG2, ARG3... 


